There is a universal need for outdoor fabrics suitable for apparel use and providing for long term insect repellency. Although many insect repellents are effective when applied to the skin as a spray or lotion, their effectiveness is known to decline with time. Furthermore, in order for an insect repellent to be effective, the insect repellent must be applied in a concentrated amount to a small area of the face, neck, or hands or on selected areas of a wearer's garment.
The effectiveness of insect repellents has been known to improve when such repellents are directly applied to fabrics which are suitable for outdoor use, and various techniques have been suggested for providing sustained release of an insect control agent.
For example, in U.S. Pat. No. 4,056,610 to Barber, et al., the invention provides for a microcapsular insecticidal composition comprising a pyrethroid and a biological synergist capable of controlling insects for up to four (4) days.
In U.S. Pat. No. 5,198,287 to Samson, the invention provides for a tent fabric coated on the inside with a composition which renders it water repellent, flame retardant and insecticide using permethrin as the insecticide. Permethrin is protected against oxygen with a plasticizer. The outside of the tent is coated with a composition which renders it water repellent and flame retardant exclusive of the insecticide. The insecticide composition has an effective life of more than six (6) months.
In U.S. Pat. No. 4,765,982 to Ronning, the invention relates to compositions, devices and methods for controlling insect activity wherein an insect control agent is self-adhered to a rough-surfaced fiber and provides extended control of insect activity. The microencapsulated insect control agents disclosed in Barber are named as the preferred insect control for use in Ronning's invention. Ronning teaches that smooth-surfaced fibers do not act as good sites for adhesion of microencapsulated insect control agents.
In U.S. Pat. No. 5,003,635 to Peterson, the invention relates to elongated flexible insect-repellent strips secured to or retained in cavities in various articles of apparel to repel insects from the person wearing such apparel.
In U.S. Pat. No. 4,833,006 to McKinney, the invention relates to a coated fabric that is flame resistant and water repellent and includes a polyfunctional isocyanate as an adhesion promoter and binder to adhere the coating to the substrate in a flake proof manner.
In U.S. Pat. No. 5,089,298 to McNally, the invention relates to the impregnation of Battle Dress Uniforms used by the U.S. Military with amylopectin fabric wrinkle inhibitor and permethrin insect/arthropod repellent in combination.
In U.S. Pat. No. 3,859,121 to Yeadon et al., the invention relates to textiles impregnated with insect-repellent compositions including piperonyl butoxide and pyrethrin, wetting agent, thickener and an agent for preventing migration of the piperonyl butoxide and pyrethrin repellent into foods stored in contact with the textiles and for otherwise retaining the repellent in the textiles.
An amine insect repellent such as, for example, N,N'-diethyl-m-toluamide (DEET) is an effective insect repellent. In addition, it is believed that DEET is generally environmentally safe and leaves no or minimal harmful residues. DEET has been found to be stable at both reduced and elevated temperatures and under storage conditions. DEET is effective on biting flies, chiggers, deerflies, fleas, leeches, mosquitoes, and ticks. Several factors influence the efficacy of DEET as an insect repellent, such as, for example, extreme environmental conditions, the extent of absorption and elimination, the type of repellent composition, and the avidity of the test species. Typically, the efficacy of DEET tends to be reduced by increased perspiration and external water sources such as rain.